fc_pipe now muxes video + that frame's embedded audio into ONE streaming AVI
container on stdout, so ffmpeg reads a SINGLE input (-f avi -i pipe:0) instead
of a raw video pipe + a separate live audio FIFO. The two-live-pipe design
deadlocked ffmpeg (it stalled forever probing input 0); a single interleaved
stream removes that failure mode entirely.
fc_pipe.c:
- New AVI mode (argv[3] == "--avi"/"avi"). Writes RIFF('AVI ') + LIST(hdrl)
{ avih + strl(vids: strh+BITMAPINFOHEADER UYVY 16bpp) + strl(auds:
strh+WAVEFORMATEX PCM s16le 48k 2ch) } + LIST(movi) once, then per ring
entry a '00dc' video chunk followed by a '01wb' audio chunk (LE sizes,
even-pad). RIFF/movi sizes use the 0x7FFFFFFF streaming sentinel (pipe is
unseekable); dwFlags has NO index bits. Frame-coupled by construction: both
chunks come from the SAME ring entry in one read-loop iteration.
- dwScale/dwRate = fps_den/fps_num (video) and nBlockAlign/nAvgBytesPerSec
(audio). If a frame has audio_size 0, emits one frame-interval of silence
(round(48000*fps_den/fps_num) samples) so the audio timeline tracks video
and ffmpeg never starves on the audio demuxer.
- Legacy raw video-only mode retained when no avi flag is given. The old
split-stdout/audio-FIFO threaded path is removed (it was the deadlock).
fc_client.{h,c}:
- Add fc_consumer_info() / fc_stream_info_t to expose the slot header's
width/height/fps/audio params to fc_pipe for the AVI header.
capture-manager.js (_buildInputArgs deltacast/sdi framecache branch):
- Spawn fc_pipe with "--avi" (no audio FIFO). Remove the mkfifo + audio-FIFO
creation for this path.
- inputArgs: ONE input -thread_queue_size 512 -f avi [AUDIO_OFFSET_MS] -i pipe:0
(was: -f rawvideo -i pipe:0 AND -f s16le -ar 48000 -ac 2 -i <fifo>).
- audioInputIndex 0, audioFifo null. Growing VC-3/HEVC builders already map
[0:v] and audioMap 0🅰️0?; with one AVI input that resolves to 0:v / 0:a.
Validated on zampp3 against the LIVE deltacast-0-0 slot: fc_pipe --avi | ffmpeg
-f avi -i pipe:0 -> dnxhd/pcm_s24le MXF gives 360 video / 360 audio packets in
6.006s (no stall at 2 frames). A synthetic 1 kHz sine slot through the same
path yields mean_volume -9 dB / max -6 dB, proving the muxer carries real audio
end-to-end (the live SDI input currently carries no embedded audio, so the
bridge's silence fallback reads -91 dB — upstream of the muxer).
Re-engineer the framecache so each video frame carries its own SDI-embedded
audio through ONE transport, eliminating the "audio ahead of video" offset at
the root: there is no longer a second independent audio buffer/FIFO that can
race ahead of video.
slot.h (FC_VERSION 1 -> 2):
- Per ring entry data region is now [video frame_size][audio FC_MAX_AUDIO_BYTES].
- fc_frame_t: the former _pad u32 is REUSED as audio_size (header still 24B).
- Header gains audio_max_bytes / audio_rate / audio_channels (self-describing).
- New fc_entry_stride()/fc_frame_audio() helpers; shm size includes audio.
- Readers/writer check version == FC_VERSION and FAIL SAFE on mismatch so an
old reader against a new writer (or vice-versa) refuses rather than misparses.
slot.c: populate audio header fields; add fc_slot_write_av(); version gate in open.
fc_client.[ch]: fc_frame_ref_t gains audio/audio_size; copy buffer holds
video+audio; both copied from the SAME entry in one read -> frame-locked.
fc_pipe.c: now <slot_id> <wait_ms> <audio_fifo_path>; per ring entry writes
video -> stdout AND that frame's audio -> the audio FIFO IN LOCKSTEP from one
cursor read (no second buffer to drift). Auto-reattaches FIFO on EPIPE.
deltacast-bridge:
- SILENT-AUDIO FIX: audio_extract_init now configures ONLY pAudioChannels[0]
of group 0 as one stereo pair (Mode=STEREO, BufferFormat=AF_16, pData=buf),
leaving pAudioChannels[1] ZEROED, exactly like Deltacast's own FFmpeg fork
(libavdevice/videomaster_common.c init_audio_info). The prior JOINED code
ALSO set channel[1].Mode/BufferFormat=STEREO/AF_16, declaring a second pair
the signal does not carry -> VHD_SlotExtractAudio returned zero samples ->
-91 dB silent audio. DataSize is (re)set to capacity before each extract.
- VHD_SDI_SP_INTERFACE now set from the channel-detected interface
(VHD_SDI_CP_INTERFACE) before StartStream, per the same fork — required for
embedded-audio extraction on JOINED SDI streams.
- fc_writer.[ch]: add fc_writer_write_av(); struct/stride bumped to v2.
- video_thread (framecache path) extracts each frame's audio from the SAME
locked JOINED slot and writes BOTH via fc_writer_write_av. Silence fallback
at the source: a frame with no embedded audio gets one frame-interval of
silence so the audio timeline length always equals the video timeline length.
- The separate audio FIFO + audio_thread + apcm ring are retained ONLY for the
legacy (-DLEGACY_FIFO / framecache-unreachable) fallback; on the primary
framecache path the bridge no longer owns the audio FIFO.
capture-manager.js: deltacast/sdi framecache branch now CREATES the audio FIFO
and passes its path to fc_pipe (argv[3]); ffmpeg keeps two raw inputs
(rawvideo pipe:0 + s16le 48k input 1) but both are now fed frame-locked from
the same ring entry. Stale-audio pre-flush retained as harmless safety.
All changes versioned; mismatched binaries refuse to attach (fail safe).
Zac Gaetano
